Knuckle for a self-steering axle/suspension system

ABSTRACT

A knuckle for a heavy-duty vehicle self-steering axle/suspension system that includes integrally formed structure for mounting components of a drum brake system. The knuckle includes a spindle that is welded directly to the knuckle and a discrete tie rod arm bolted to the knuckle.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional PatentApplication Ser. No. 63/126,193, filed on Dec. 16, 2020.

BACKGROUND Technical Field

The subject disclosure generally relates to axle/suspension systems forheavy-duty vehicles. More particularly, the subject disclosure relatesto self-steering axle/suspension systems for heavy-duty vehicles. Morespecifically, the subject disclosure relates to a knuckle for aheavy-duty vehicle self-steering axle/suspension system that includesintegrally formed structure for mounting components of a drum brakesystem, which eliminates complex manufacturing processes and componentsfor preparing a spindle end of the knuckle to enable mounting a discretebrake spider and machining of multiple interfaces on the spindle end toposition and attach the discrete brake spider, thereby reducingmanufacturing complexity and cost. The knuckle includes a spindle thatis a forged, machine finished, and then friction welded directly to theknuckle with only the single friction weld, which eliminates the need toutilize multiple welds to attach the spindle to the knuckle, therebyreducing manufacturing cost and increasing the overall strength of thespindle. Also, by integrating structure for mounting drum brake systemcomponents into the knuckle, the distance from a king pin to a bearingshoulder of the spindle, and thus the distance from the king pin to avertical centerline of a wheel attached to a wheel hub rotatably mountedon bearings attached to the spindle, is minimized. This reduces stresson the knuckle and the pivotal connection of the knuckle to an end pieceof a steerable axle, thereby increasing the overall strength andreducing fatigue of the knuckle and pivotal connection of the knuckle tothe steerable axle, and reducing the risk for potential prematurefailure of the knuckle and/or pivotal connection of the knuckle to thesteerable axle. In addition, the knuckle includes a discrete tie rod armbolted to the knuckle via axial and radial bolting in a manner thatminimizes the overall size and weight of the knuckle, while providing asturdy structure that resists overload conditions and reduces theoverall weight of the heavy-duty vehicle, provides desired turn angle ofthe knuckle and mounted wheel, and provides the knuckle with a robuststructure capable of being utilized on self-steering axle/suspensionsystems with varying components and configurations.

Background Art

Self-steering axle/suspension systems for heavy-duty vehicles are wellknown in the art. Heavy-duty vehicles include trucks andtractor-trailers or semi-trailers, and trailers thereof. Each heavy-dutyvehicle generally includes a frame, from which at least oneaxle/suspension system is suspended, such as a self-steeringaxle/suspension system. In recent years, self-steering axle/suspensionsystems, particularly in the medium and heavy-duty truck andsemi-trailer industry, have become quite popular. Such self-steeringaxle/suspension systems are typically used to distribute the loadcarried by the axles of the heavy-duty vehicle when the self-steeringaxle/suspension systems are in a lowered or operating position. When theheavy-duty vehicle has little or no load, the self-steeringaxle/suspension systems often employ lift systems and can be lifted sotires associated with the self-steering axle/suspension system do notcontact the ground or road surface. The self-steering axle/suspensionsystems may also be of a non-liftable type. When the self-steeringaxle/suspension systems are in the lowered or operating position withthe tires in contact with a ground or road surface, the self-steeringfeature provides a mechanism by which the tires may better follow thepath of travel when the heavy-duty vehicle is turning, while stillhelping to carry the load of the heavy-duty vehicle. In trailing armself-steering axle/suspension systems, it is known that if a steerableaxle is installed with the proper pitch or caster angle, the drag of themounted wheels will cause the steerable axle to steer automatically inresponse to steering of the vehicle.

Such self-steering axle/suspension systems are generally similar in thateach typically includes a steerable axle with a central axle tubesupported by a pair of transversely-spaced trailing arm beams, which arewelded or otherwise rigidly attached to the central axle tube. Eachtrailing arm beam is pivotally connected at its front end to arespective one of a pair of transversely-spaced frame hangers, which inturn are rigidly attached to and depend from respective main members ofa frame of the heavy-duty vehicle. The self-steering axle/suspensionsystem often includes a pair of shock absorbers and a pair of airsprings. Each shock absorber extends between and is mounted on arespective one of the beams and is attached to its corresponding hangeror main member of the heavy-duty vehicle frame. Each air spring extendsbetween and is mounted on a rear end of a respective one of the beamsand a corresponding main member of the heavy-duty vehicle frame.Together, the shock absorbers and air springs provide desired ridecharacteristics to the self-steering axle/suspension system, and thusthe heavy-duty vehicle.

To allow wheels attached to the steerable axle of the self-steeringaxle/suspension system to turn, the steerable axle also includes a pairof end pieces, which are attached to respective outboard ends of thecentral axle tube by suitable means, such as welds. The self-steeringaxle/suspension system further includes a pair of prior art knuckles,which are pivotally connected to respective end pieces of the steerableaxle via king pins disposed through vertically aligned openings formedin the knuckles and the end pieces. Each prior art knuckle includes aspindle end, which is rigidly attached to the outboard surface of theknuckle by any suitable means, such as welding or fasteners. A wheel endassembly is rotatably mounted on the spindle end in a manner well knownin the art. More specifically, the wheel end assembly includes a bearingassembly with an inboard bearing and an outboard bearing that aremounted on the outboard end of the spindle end. A spindle nut assemblyis threaded onto the outboard end of the spindle end and secures theinboard and outboard bearings in place. A wheel hub of the wheel endassembly is mounted on the inboard and outboard bearings for rotationrelative to the spindle end, as is known. A hub cap is mounted on theoutboard end of the wheel hub and closes the outboard end of the wheelhub, and thus the wheel end assembly. A plurality of threaded fastenersor studs and mating nuts are used to mount a rim or a pair of rims,depending on specific design considerations of the wheel end assembly,to the wheel hub. A tire is mounted on each rim, as is known. Togetherthe wheel rim with mounted tire are collectively referred to as a“wheel” for purposes of this disclosure.

Each prior art knuckle includes a pivot arm or tie rod arm, which isformed with a pair of longitudinally spaced openings. A tie rod isconnected to the rearwardmost one of the pair of openings via afastener. A coil over spring is connected at a first end to thefrontwardmost opening of the tie rod arm via a fastener. The second endof the coil over spring is connected to a bracket, which in turn isconnected to the central axle tube of the steerable axle by any suitablemeans, such as welds and/or fasteners.

When the wheels mounted on the prior art knuckles turn, the knucklespivot relative to the end pieces of the steerable axle about the kingpins. When the wheels turn toward the driver side of the vehicle to makea forward left turn, the driver side knuckle pivots toward the driverside end piece of the steerable axle about the pivotal connection to theend piece via the king pin, while the passenger side knuckle pivots awayfrom the passenger side end piece of the steerable axle about thepivotal connection to the end piece via the respective king pin.Conversely, when the wheels mounted on the prior art knuckles turntoward the passenger side of the vehicle to make a forward right turn,the driver side knuckle pivots away from the driver side end piece ofthe steerable axle about the pivotal connection to the end piece via theking pin, while the passenger side knuckle pivots toward the passengerside end piece of the steerable knuckle about the pivotal connection tothe end piece via the respective king pin. Because the driver side andpassenger side knuckles are connected to one another via the tie rod,each wheel attached to their respective spindle end are maintained insubstantially parallel alignment to one another during a forward rightand forward left vehicle turn, with the passenger side wheel turning ata slightly larger angle than the driver side wheel in a forward rightvehicle turn and the driver side wheel turning at a slightly largerangle than the passenger side wheel in a forward left vehicle turn. Inthis manner, the self-steering axle/suspension system aids inmaneuvering the heavy-duty vehicle during turns.

Self-steering axle/suspension systems often incorporate drum brakesystems to provide braking to the heavy-duty vehicle. When utilized withheavy-duty vehicle self-steering axle/suspension systems, components ofthe drum brake systems are typically incorporated into or mounted oncomponents of self-steering axle/suspension systems, such as the spindleends of prior art knuckles. The drum brake systems generally include apair of drum brake assemblies incorporated into respective outboard endsof the self-steering axle/suspension system. More specifically, eachdrum brake assembly typically includes a brake drum attached to a wheelhub of the wheel end assembly rotatably mounted on an outboard end ofthe spindle end of the respective prior art knuckle. The drum brakeassembly also includes a pair of brake shoes housed within, and radiallyspaced from the interior braking surface of the brake drum. The brakeshoes are pivotally connected to a discrete brake spider fixedlyattached to the spindle end inboardly of the wheel end assembly. Eachbrake shoe is connected to a respective roller on the end of the brakeshoe opposite the pivotal connection. An S-cam attached to the outboardend of a cam shaft of a cam shaft assembly attached to the knuckleengages the rollers for actuation of the brake shoes.

During operation, when the drum brake system of the heavy-duty vehicleis actuated, such as by pressurization of a brake air chamberoperatively connected to the cam shaft, the cam shaft rotates, therebyrotating the S-cam. The rotation of the S-cam, in turn, overcomes one ormore brake return springs connected between the brake shoes, forcingbrake linings of the brake shoes radially outward such that brakelinings of the brake shoes contact the interior braking surface of thebrake drum, thereby creating friction to slow or stop the heavy-dutyvehicle. Once the drum brake system is no longer actuated, the camshaft, and thus the S-cam, rotates back, allowing the brake returnspring(s) to re-establish a radially-spaced relationship between thebrake linings of the brake shoes and interior braking surface of thebrake drum.

While generally suitable for their intended purpose, such prior artknuckles for self-steering axle/suspension systems have certaindisadvantages, drawbacks, and limitations. For example, such prior artknuckles typically utilize discrete brake spiders that are welded orotherwise rigidly attached to the spindle ends of the knuckles when theself-steering axle/suspension system employs a drum brake system. Theuse of such discrete brake spiders often includes a complexmanufacturing process that first requires an axle end to be cut off andremoved from a straight axle with spindles friction mounted to a centraltube, such that the axle end includes a spindle and a portion of acentral tube, referred to herein as a “spindle end”. Multiple interfacesmay be machined on the spindle end to enable positioning of the discretebrake spider. The spindle end is then welded or otherwise rigidlyattached to a body of the prior art knuckle. The discrete brake spideris then positioned and welded on the spindle end between the location ofthe inboard bearing of the bearing assembly on which the wheel hub isrotatably mounted and the inboard end of the spindle end. This complexmanufacturing process required to prepare the spindle end of the priorart knuckle for mounting and attachment of the discrete brake spiderincreases the overall cost and complexity to manufacture the prior artknuckle.

In addition, when the spindle end is prepared by this complexmanufacturing process and attached to the prior art knuckle, four weldsare typically required, the first weld being between the central tubeand spindle during preparation of the spindle end and the second weldbeing between the inboard end of the spindle end and the body of theprior art knuckle. The third and fourth welds attach the outboard andinboard side of the brake spider to the spindle end. Because the priorart knuckle requires four welds to attach the spindle end and brakespider, the overall strength of the spindle end is reduced, whichincreases stress and fatigue of the spindle and can potentially resultin reduced life of the spindle end, and thus the prior art knuckle.

Moreover, with such prior art knuckles, to support attachment of thebrake spider, the overall length of the spindle end must be undesirablyincreased to provide space for weld torch access for attaching the brakespider to the spindle end. This increased length of the axle end resultsin the wheel hub and attached wheel being positioned further outboardlyfrom the pivotal connection of the knuckle to the end piece of thesteerable axle via the king pin, which increases stress and fatigue ofthe knuckle and the pivotal connection of the knuckle to the end piece,which can potentially result in reduced life or premature failure of theknuckle and/or pivotal connection of the knuckle to the end piece of thesteerable axle.

Furthermore, such prior art knuckles often include tie rod arms that arewelded to the body of the knuckle. Such welded connection of the tie rodarm to the body of the knuckle can potentially fail when operating inharsh or abusive environments, such as during off-road operation of theself-steering axle/suspension system, for example, on a constructionsite, or during an overload condition on the knuckle. Alternatively,such prior art knuckles have employed a pair of axial bolts disposedthrough respective aligned axial openings formed in the tie rod arm andthe body of the knuckle to secure the tie rod arm to the body. Suchattachment configurations typically require the knuckle to have arelatively large body and/or a larger tie rod arm to support suchmounting, which results in overall increased weight of the self-steeringaxle/suspension system, and thus the heavy-duty vehicle. Moreover, dueto packaging constraints, such configurations can also undesirably limitthe degree of turn angle of the knuckle, and thus the associated wheel.

Thus, there is a need in the art for a knuckle for a heavy-duty vehicleself-steering axle/suspension system that includes an integrally formedstructure for mounting components of a drum brake system, whicheliminates complex manufacturing processes and components for preparinga spindle end of the knuckle capable of mounting a discrete brake spiderto position and attach the discrete brake spider on the spindle end,thereby reducing manufacturing complexity and cost. There is also a needin the art for a knuckle that includes a spindle that is a forged,machine finished, and then friction welded directly to the knuckle withonly the single friction weld, which eliminates the need to utilizemultiple welds to attach the spindle to the knuckle, and multiple weldsto attach a discrete brake spider to the spindle of the knuckle, therebyreducing manufacturing cost and increasing the overall strength of thespindle. There is also a need in the art for a knuckle that minimizesthe distance from a king pin to a bearing shoulder of the spindle, andthus the distance from the king pin to a vertical centerline of a wheelattached to a wheel hub rotatably mounted on bearings attached thespindle, which reduces stress on the knuckle and the pivotal connectionof the knuckle to an end piece of a steerable axle, thereby increasingthe overall strength and reducing fatigue of the knuckle and pivotalconnection of the knuckle to the steerable axle, and reducing the riskfor potential premature failure of the knuckle and/or pivotal connectionof the knuckle to the steerable axle. In addition, there is also a needin the art for a knuckle that includes a discrete tie rod arm connectedto the knuckle in a manner that minimizes the overall size and weight ofthe knuckle, while providing a sturdy structure that resists overloadconditions, which reduces the overall weight of the heavy-duty vehicle,provides desired turn angle of the knuckle and mounted wheel, andprovides the knuckle with a robust structure capable of being utilizedon self-steering axel/suspension systems with varying components andconfigurations.

The knuckle for a heavy-duty vehicle self-steering axle/suspensionsystem of the subject disclosure satisfies these needs and overcomes theabove described disadvantages, drawbacks, and limitations, and will nowbe described.

BRIEF DESCRIPTION OF THE SUBJECT DISCLOSURE

An objective of the subject disclosure is to provide a knuckle for aheavy-duty vehicle self-steering axle/suspension system that eliminatescomplex manufacturing processes and components for preparing a spindleend of the knuckle to enable mounting of a discrete brake spider andmachining of multiple interfaces on the spindle end to position andattach the discrete brake spider, thereby reducing manufacturingcomplexity and cost.

Another objective of the subject disclosure is to provide a knuckle fora heavy-duty vehicle self-steering axle/suspension system with aconfiguration/structure that eliminates the need to utilize multiplewelds to attach the spindle to the knuckle, thereby reducingmanufacturing cost and increasing the overall strength of the spindle.

Yet another objective of the subject disclosure is to provide a knucklefor a heavy-duty vehicle self-steering axle/suspension system thatminimizes the distance from a king pin to a bearing shoulder of thespindle, and thus the distance from the king pin to a verticalcenterline of a wheel attached to a wheel hub rotatably mounted onbearings attached to the spindle, thereby reducing stress on the knuckleand pivotal connection of the knuckle to a steerable axle of theself-steering axle/suspension system and increasing the overall strengthand reducing fatigue of the knuckle and pivotal connection of theknuckle to the steerable axle, and reducing the risk for potentialpremature failure of the knuckle and/or pivotal connection of theknuckle to the steerable axle.

Another objective of the subject disclosure is to provide a knuckle fora heavy-duty vehicle self-steering axle/suspension system that includesa discrete tie rod arm connected to the knuckle in a manner thatminimizes the overall size and weight of the knuckle, while providing asturdy structure that resists overload conditions and reduces theoverall weight of the heavy-duty vehicle, provides desired turn angle ofthe knuckle and mounted wheel, and provides the knuckle with a robuststructure capable of being utilized on self-steering axle/suspensionsystems with varying components and configurations.

These objectives and other are achieved by the knuckle for a heavy-dutyvehicle self-steering axle/suspension system of the subject disclosure,which includes: a body, the body receiving a king pin of theself-steering axle/suspension system for pivotal connection of theknuckle to an axle of the self-steering axle/suspension system; aspindle extending from an outboard surface of the body; and drum brakesystem component mounting structure, the drum brake system componentmounting structure being integrally formed with the body and mountingone or more components of the drum brake system.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

An exemplary embodiment of the subject disclosure, illustrative of thebest mode in which Applicant has contemplated applying the principles,is set forth in the following description and is shown in the drawings.

FIG. 1 is a perspective view of a trailing arm heavy-duty vehicleself-steering axle/suspension system that employs a pair of prior artknuckles, showing a discrete brake spider of a drum brake assembly of adrum brake system attached to a spindle end of each knuckle;

FIG. 2 is a perspective view of an exemplary embodiment knuckle for aheavy-duty vehicle self-steering axle/suspension system of the subjectdisclosure, viewed looking in an inboard direction, showing componentsof a drum brake assembly of a drum brake system mounted to structureintegrated into the knuckle;

FIG. 3 is a perspective view of the exemplary embodiment knuckle withmounted drum brake assembly components shown in FIG. 2, viewed lookingin an outboard direction;

FIG. 4 is an exploded perspective view of the exemplary embodimentknuckle shown in FIG. 2, showing a spindle of the knuckle removed fromthe knuckle;

FIG. 5 is an exploded perspective view of the exemplary embodimentknuckle shown in FIG. 2, showing a tie rod arm of the knuckle andassociated mounting bolts removed from the knuckle; and

FIG. 6 is a perspective view of the exemplary embodiment knuckle shownin FIG. 2, showing the orientation of an axle end piece of a steerableaxle of the self-steering axle/suspension system relative to theknuckle.

Similar numerals and characters refer to similar components throughoutthe drawings.

DETAILED DESCRIPTION OF THE SUBJECT DISCLOSURE

In order to better understand the knuckle for a heavy-duty vehicleself-steering axle/suspension system of the subject disclosure and theenvironment in which it operates, a heavy-duty vehicle self-steeringaxle/suspension system that employs a pair of prior art knuckles isshown in FIG. 1, and is indicated generally at reference numeral 10.

Self-steering axle/suspension system 10 includes a steerable axle 20.Steerable axle 20 includes a central axle tube 34 supported by a pair oftransversely-spaced trailing arm beams 40, to which the central axletube is welded or otherwise rigidly attached. Each trailing arm beam 40is pivotally attached at its front end to a respective one of a pair oftransversely-spaced frame hangers 42 that are rigidly attached to anddepend from respective main members (not shown) of a frame (not shown)of the heavy-duty vehicle. Self-steering axle/suspension system 10includes a pair of air springs 46. Each air spring 46 extends betweenand is mounted on a rear end of a respective beam 40 and in turn isattached to a respective main member of the heavy-duty vehicle frame.Self-steering axle/suspension system 10 also includes a pair of shockabsorbers 44. Each shock absorber 44 extends between and is mounted on arespective one of beams 40 and a corresponding hanger 42. Together, airsprings 46 and shock absorbers 44 help provide desirable ridecharacteristics to self-steering axle/suspension system 10, and thus theheavy-duty vehicle, during operation, as is known.

Steerable axle 20 also includes a pair of end pieces 54, which areattached to respective outboard ends of central axle tube 34 of thesteerable axle by any suitable means, such as welds. Each end piece 54enables pivotal connection of a prior art knuckle 58, as will bedescribed below. Inasmuch as prior art knuckles 58 are similar, forpurposes of conciseness and clarity, only a single prior art knuckle andits pivotal connection to a respective end piece 54 of steerable axle 20will be described.

Prior art knuckle 58 includes a body 67 and a pair of arms 62 (only oneshown) extending frontward/inboardly therefrom. Arms 62 of knuckle 58are vertical aligned with one another such that there is a gap (notshown) between the arms. Arms 62 are formed with respective verticalopenings 59 (only one shown) that are vertically aligned with eachother. End piece 54 of steerable axle 20 is also formed with a verticalopening (not shown) and is disposed in the gap between arms 62 ofknuckle 58 such that the opening is in vertical alignment with verticalopenings 59 of the arms. A king pin 56 is disposed through the alignedvertical openings 59 of arms 62 of knuckle 58 and the vertical openingof end piece 54 of steerable axle 20 to pivotally connect the knuckle tothe end piece.

Prior art knuckle 58 includes a spindle end 68, which is rigidlyattached to the outboard surface of the knuckle by suitable means, suchas welding or fasteners. A wheel end assembly (not shown) is rotatablymounted on spindle end 68 in a manner well known in the art. Morespecifically, the wheel end assembly includes a bearing assembly (notshown) with an inboard bearing (not shown) and an outboard bearing (notshown) that are mounted on the outboard end of spindle end 68. A spindlenut assembly (not shown) is threaded onto the outboard end of spindleend 68 and secures the inboard and outboard bearings in place. A wheelhub (not shown) of the wheel end assembly (not shown) is mounted on theinboard and outboard bearings for rotation relative to spindle end 68,as is known. A hub cap (not shown) is mounted on the outboard end of thewheel hub and closes the outboard end of the wheel hub, and thus thewheel end assembly. A plurality of threaded fasteners or studs (notshown) and mating nuts (not shown) are used to mount a single rim (notshown) or a pair of rims (not shown), depending on specific designconsiderations of the wheel end assembly, to the wheel hub. A tire (notshown) is mounted on each rim, as is known.

Prior art knuckle 58 includes a tie rod arm or pivot arm 60, which isrigidly attached to body 67 of the knuckle by suitable means, such aswelds. Tie rod arm 60 is formed with a pair of longitudinally spacedopenings (not shown). A tie rod 66 is pivotally connected to therearwardmost one of the pair of openings via a fastener 61 (only oneshown). A coil over spring 64 is connected to the frontwardmost openingof tie rod arm 60 via a fastener 63. Coil over spring 64 in turn isconnected to a bracket 65, which is attached to central axle tube 34 ofsteerable axle 20 by any suitable means, such as welds and/or fasteners.Coil over spring 64 aids in returning the wheels attached toself-steering axle/suspension system 10 to a straight direction after avehicle turn, as is known.

When the wheels mounted on prior art knuckle 58 turn, the knuckle pivotsrelative to end piece 54 of steerable axle 20 about king pin 56. Whenthe heavy-duty vehicle makes a forward left turn, the wheels turn towardthe driver side of the vehicle and the driver side knuckle 58 pivotstoward end piece 54 about the pivotal connection via king pin 56, whilethe passenger side knuckle pivots away from its respective end pieceabout the pivotal connection via the respective king pin. Conversely,when the heavy-duty vehicle makes a forward right-hand turn, the wheelsturn toward the passenger side of the vehicle and the passenger sideknuckle 58 pivots toward its respective end piece 54 about the pivotalconnection via king pin 56, while the driver side knuckle pivots awayfrom its respective end piece about the pivotal connection via therespective king pin. Because the driver side and passenger side knuckles58 are connected to one another via tie rod 66, the respective wheelsmounted on the knuckles are maintained in substantially parallelalignment with one another during a forward left turn or a forward rightturn of the heavy-duty vehicle, with the driver side wheel turning at aslightly larger angle than the passenger side wheel in a forward leftturn and the passenger side wheel turning at a slightly larger anglethan the driver side wheel in a forward right turn.

Self-steering axle/suspension system 10 incorporates components of adrum brake system 70 to provide braking to the heavy-duty vehicle. Drumbrake system 70 includes a pair of drum brake assemblies 72 that areincorporated into respective outboard ends of self-steeringaxle/suspension system 10, as will be described in detail below.Inasmuch as drum brake assemblies 72 are similar, for purposes ofconciseness and clarity, only a single drum brake assembly will bedescribed.

Drum brake assembly 72 includes a discrete brake spider 80, which isdisposed over spindle end 68 of prior art knuckle 58 via a central bore82 formed in the brake spider and is immovably attached to the spindleend by suitable means, such as welds. Drum brake assembly 72 includes acam shaft assembly 74 mounted to prior art knuckle 58 and brake spider80. More specifically, cam shaft assembly 74 includes a cam tube 76. Theoutboard end of cam tube 76 is disposed through a cam tube bore 85formed in brake spider 80 and is attached thereto via any suitablemeans, such as welds. The inboard end of cam tube 76 extends inboardlyfrom cam tube bore 85 of brake spider 80 and may be attached to body 67of knuckle 58 or brake spider 80 by suitable means, such as welds.

Cam shaft assembly 74 further includes a cam shaft (not shown), which isdisposed through and rotatably mounted within cam tube 76. Morespecifically, the cam shaft passes through outboard and inboard bushings(not shown) that are friction-fit within the outboard and inboard endsof cam tube 76, respectively. The cam shaft extends outboardly andinboardly of the outboard and inboard ends of cam tube 76, respectively.The outboard and inboard bushings within cam tube 76 enable rotation ofthe cam shaft within the cam tube. The cam shaft includes a splinedinboard end (not shown) that extends inboardly of the inboard end of camtube 76. The splined inboard end of the cam shaft meshingly engages acorresponding splined interior surface (not shown) of a slack adjuster(not shown), as is known in the art. Cam shaft assembly 74 furtherincludes an S-cam 78 that is attached to the outboard end of the camshaft, such that the S-cam is exposed and is located outboard of andadjacent to the outboard end of cam tube 76.

Drum brake assembly 72 further includes a brake air chamber 88 that isin fluid communication with an air source located on the heavy-dutyvehicle via a pneumatic line (not shown). Brake air chamber 88 isutilized to actuate other components of the drum brake assembly toprovide braking to the heavy-duty vehicle, as is known. Brake airchamber 88 is mounted to a bracket (not shown) that may be rigidlyattached to the inboard end of cam tube 76 or knuckle 58 in a knownmanner. A push rod 89 (only one shown) slidably and operativelyconnected to brake air chamber 88 extends rearwardly from the brake airchamber, and in turn is pivotally connected to the slack adjuster.

During braking of the heavy-duty vehicle, air is introduced into brakeair chamber 88 from the air source located on the vehicle via thepneumatic line connected between the air source and the brake airchamber. As the air pressure within brake air chamber 88 increases, pushrod 89 is forced rearwardly. Because push rod 89 is pivotally connectedto the slack adjuster, and the cam shaft is connected to the slackadjuster via the splined connection and is rotatably mounted within camtube 76, rearward movement of the push rod causes rotation of the camshaft within the cam tube. This in turn causes rotation of S-cam 78attached to the outboard end of the cam shaft, which forces brakelinings of a pair of brake shoes (not shown) pivotally connected to apair of anchor pins (not shown) disposed within brake shoe mountingopenings 83 formed in brake spider 80 against an interior brakingsurface (not shown) of a brake drum (not shown) mounted to the wheel hubto slow or stop the heavy-duty vehicle.

While generally suitable for its intended purpose, prior art knuckle 58has certain disadvantages, drawbacks, and limitations. As indicatedabove, knuckle 58 utilizes brake spider 80, a discrete component, tomount other components of drum brake assembly 72, which is disposed overspindle end 68 of the knuckle via central bore 82 formed in the brakespider and is immovably attached to the spindle end by suitable means,such as welds. In order to prepare spindle end 68 to accommodatemounting and attachment of brake spider 80, a relatively complexmanufacturing process is typically employed. More specifically, in orderto prepare spindle end 68 to accommodate mounting and attachment ofbrake spider 80, a pair of spindles (not shown) are first attached to acentral tube (not shown) via a friction welding process to form astraight axle (not shown). A portion of the straight axle that includesa portion of the central tube and friction welded spindle is then cutoff of the straight axle to provide spindle end 68. Spindle end 68 isthen welded or otherwise rigidly attached to body 67 of prior artknuckle 58. Brake spider 80 is then mounted and welded on spindle end68, typically between the location of the spindle end where the inboardwheel hub bearing is mounted and the outboard side of body 67 of priorart knuckle 58.

This relatively complex manufacturing process for preparing spindle end68 for attachment to body 67 of knuckle 58 and subsequent mounting andattachment of brake spider 80 increases the overall cost to manufactureknuckle 58, and thus self-steering axle/suspension system 10. Inaddition, when spindle end 68 is attached to knuckle 58 in this manner,four welds are required, the first weld being between the central tubeand spindle during preparation of spindle end 68, and the second weldbeing between the inboard end of the spindle end and body 67 of knuckle58. The third and fourth welds attach brake spider 80 to spindle end 68,the third weld being located on the outboard side of the brake spiderand the fourth weld being located on the inboard side of the brakespider. Because four welds are required to attached spindle end 68 tobody 67 of knuckle 58 and brake spider 80 to the spindle end, theoverall strength of the spindle end and the brake spider attachmentthereto can potentially be reduced, which increases stress and fatigueof the spindle end and brake spider attachment, and potentially canresult in reduced life of the spindle end, and thus knuckle 58. Inaddition, the fourth weld, being located on the inboard side of brakespider 80, is difficult to execute because of the relatively restrictivespace between the inboard side of the brake spider and the outboardsurface of body 67 of knuckle 58, as well from interference by cam tube76 of cam shaft assembly 74. Moreover, the restrictive space andinterference by cam tube 76 of cam shaft assembly 74 may require thatthe fourth weld be interrupted in the area of the cam tube, and thusundesirably prevent the weld from being fully circumferential aboutspindle end 68 and the inboard surface of brake spider 80 adjacentcentral bore 82 of the brake spider.

Furthermore, to support mounting and attachment of brake spider 80 tospindle end 68, and thus prior art knuckle 58, the overall length of thespindle end must be undesirably increased to provide space for weldtorch access for attaching the brake spider to the spindle end. Theincreased length of spindle end 68 results in the wheel hub and attachedwheel to be positioned and rotatably mounted on the spindle end furtheroutboardly from the pivotal connection of knuckle 58 to end piece 54 ofsteerable axle 20 via king pin 56, which increases stress and fatigue ofthe knuckle and pivotal attachment of the knuckle to the end piece. Thiscan potentially result in premature failure of knuckle 58 and/or pivotalconnection of the knuckle to end piece 54 of steerable axle 20 unlessadditional support structure is incorporated into the knuckle tocompensate for the higher loads at the knuckle and pivotal connection ofthe knuckle to the steerable axle, which would undesirably increase thecost of the knuckle and overall weight of the heavy-duty vehicle.

In addition, tie rod arm 60 of prior art knuckle 58 is welded to body 67of the knuckle. The welded connection of tie rod arm 60 to body 67 ofknuckle 58 can potentially fail when operating in abusive environments,such as during off-road operation of the heavy-duty vehicleincorporating self-steering axle/suspension system 10, for example, on aconstruction site, or during an overload condition on the knuckle. Theknuckle for a heavy-duty vehicle self-steering axle/suspension system ofthe subject disclosure overcomes the above described disadvantages,drawbacks, and limitations, and will now be described.

An exemplary embodiment knuckle for a heavy-duty vehicle self-steeringaxle/suspension system of the subject disclosure is shown in FIGS. 2-6and is indicated generally at 200. Exemplary embodiment knuckle 200 isutilized in conjunction with a heavy-duty vehicle self-steeringaxle/suspension system, such as self-steering axle/suspension system 10described above. A pair of exemplary embodiment knuckles 200 arepivotally connected to respective ends of a steerable axle 120 (FIG. 6)of the self-steering axle/suspension system, as will be described indetail below. Inasmuch as exemplary embodiment knuckles 200 pivotallyconnected to respective ends of steerable axle 120 are similar, forpurposes of conciseness and clarity only one knuckle and its pivotalconnection to the steerable axle will be described in detail.

With reference to FIGS. 2-6, exemplary embodiment knuckle 200 includes abody or brake spider portion 266 formed of a suitable rigid material,such as steel. Body 266 is preferably formed by forging, but can beformed by other suitable methods depending on the materials used, suchas by casting, without affecting the overall concept or operation of thesubject disclosure. With reference to FIGS. 3 and 5-6, body 266 isformed with a first arm or lower arm 280. First arm 280 extendsinboardly from body 266 adjacent the bottom of the body. With referenceto FIGS. 3-6, body 266 is also formed with a second arm or upper arm282. Second arm 282 extends inboardly from body 266 adjacent the top ofthe body and is spaced from and in general vertical or coaxial alignmentwith first arm 280. First arm 280 and second arm 282 are preferablyintegrally formed as one-piece with body 266, for example, during aforging operation. With reference to FIGS. 3 and 5-6, first arm 280includes a vertical opening 281 for receiving a first end portion orlower portion 261 of a king pin 260 (FIG. 6). With reference to FIGS.3-6, second arm 282 includes a vertical opening 283 that is verticallyor coaxially aligned with opening 281 of first arm 280 for receiving asecond end portion or upper portion 263 of king pin 260 (FIG. 6). Withreference to FIG. 3, a bushing 286 a is disposed within opening 281 offirst arm 280 and a bushing 286 b is disposed within opening 283 ofsecond arm 282.

With reference to FIGS. 3-6, body 266 of exemplary embodiment knuckle200 is also formed with tie rod arm mounting structure 270. Withreference to FIG. 5, tie rod arm mounting structure 270 is formed withand extends generally rearward from first arm 280 and is formed with andextends inboardly from body 266 of exemplary embodiment knuckle 200.Mounting structure 270 includes a horizontally planar tie rod armattachment surface 272. Attachment surface 272 includes a threadedvertical opening 273 that extends vertically into mounting structure270, the importance of which will be described in detail below. Body 266of knuckle 200 is formed with a vertically planar tie rod arm attachmentsurface 267 on its inboard side. Attachment surface 267 includes athreaded axial opening 271 (FIGS. 4-5) that extends outboardly throughbody 266, the importance of which will also be described in detailbelow.

With reference to FIG. 6, king pin 260 is utilized to pivotally connectexemplary embodiment knuckle 200 to steerable axle 120 of theself-steering axle/suspension system (not shown). Steerable axle 120 isgenerally similar in structure and function to steerable axle 20described above, except that it employs a pair of end pieces 140 thatinclude structure different than that of end pieces 54. Like steerableaxle 20, steerable axle 120 includes a central axle tube (not shown)attached to a pair of transversely-spaced trailing arm beams (not shown)of the self-steering axle/suspension system, such as beams 40 ofself-steering axle/suspension system 10 described above, by any suitablemeans, such as welds and/or fasteners. Each end piece 140 is attached toa respective outboard end of the central axle tube of steerable axle120, which will be described in detail below. Inasmuch as end pieces 140are similar, for purposes of conciseness and clarity only one end piecewill be described in detail.

With continued reference to FIG. 6, end piece 140 of steerable axle 120is forged of a suitable sturdy material, such as steel, and is thenmachine finished. End piece 140 includes a main portion 142 formed witha vertical opening 144 extending completely through the main portion forreceiving a central portion (not shown) of king pin 260. End piece 140includes an axle attachment portion or plug portion 146 that extendsinboardly from main portion 142 of the end piece, such that an axialcentral axis A of the end piece extends in a direction axial to avertical or coaxial central axis C of opening 144. Axle attachmentportion 146 of end piece 140 has an outer periphery that is shaped andsized to be press fit within the end portion of the central axle tube ofsteerable axle 120. In the illustrated example, axle attachment portion146 has a substantially cylindrical configuration and solid structure,but can have different configurations and/or structures, such as asquare configuration and/or a hollow structure, depending on the shapeand configuration of the central axle tube of steerable axle 120,without affecting the overall concept or operation of the subjectdisclosure. The central axle tube may have surface means near an end ofthe central axle tube for welding end piece 140 to the central axle tubeof steerable axle 120 to prevent relative rotation, such as one or morewindows (not shown). It is contemplated that, depending on theconfiguration and/or structure of end piece 140 and/or steerable axle120, the end piece could be attached to the axle central tube of thesteerable axle by means other than an interference fit, such as byfriction welding, without affecting the overall concept or operation ofthe subject disclosure.

Main portion 142 of end piece 140 is disposed in a gap formed betweenvertically or coaxially spaced-apart first arm 280 and second arm 282 ofexemplary embodiment knuckle 200, such that when the main portion of theend piece is positioned between the first arm and the second arm,vertical opening 144 vertically or coaxially aligns with openings 281and 283 of the first arm and second arm, respectively. King pin 260 isdisposed through vertically or coaxially aligned opening 283 of secondarm 282 of knuckle 200, opening 144 of end piece 140 of steerable axle120, and opening 281 of first arm 280 of the knuckle. King pin 260 isimmovable relative to main portion 142 of end piece 140 of steerableaxle 120 via a tapered draw key (not shown), which engages a respectiveflat (not shown) that may be machined on the inboard side of the kingpin in the central portion of the king pin. The tapered draw key iswedged between the respective flat machined in the inboard side of theking pin and end piece 140 of steerable axle 120 about opening 144, suchthat the king pin is forced to contact the outboard side of the openingto immovably secure the king pin to the end piece. Alternatively, kingpin 260 may be immovable relative to main portion 142 of end piece 140of steerable axle 120 via more than one tapered draw key. For example,king pin 260 may be immovable relative to main portion 142 of end piece140 of steerable axle 120 via a pair of tapered draw keys (not shown),which each engage respective flats (not shown) machined on the bottominboard side of the king pin and the top outboard side of the king pinin the central portion of the king pin. In such a configuration, thetapered draw keys are wedged between the respective flats machined inthe top outboard side of king pin 260 and the bottom inboard side of theking pin and end piece 140 of steerable axle 120 about opening 144, suchthat the king pin is forced to contact the inboard side of the openingnear the top of the opening and the outboard side of the opening nearthe bottom of the opening to immovably secure the king pin to the endpiece. Once disposed within vertically or coaxially aligned opening 283of second arm 282 of knuckle 200, immovably secured within opening 144of end piece 140 of steerable axle 120, and disposed within opening 281of first arm 280 of the knuckle, king pin 260 extends substantiallyalong vertical central axis C (FIG. 6), and thus is substantiallyperpendicular to axial central axis A of end piece 140 (FIG. 6), andthus steerable axle 120. In this manner, exemplary embodiment knuckle200 is pivotally mounted about king pin 260 in frontward and rearwarddirections.

A cap (not shown) is disposed within a counterbore 284 (FIGS. 3-6)formed in second arm 282 of exemplary embodiment knuckle 200 adjacentopening 283 and seals the upper end of the opening to preventcontaminants from the environment in which the heavy-duty vehicleoperates from entering the pivotal connection of the knuckle to endpiece 140 of steerable axle 120 via the king pin 260. An upper oroutermost surface (not shown) of the cap may be substantially flush withan upper surface 285 (FIGS. 3-6) of second arm 282 or can be spacedslightly upward or downward from the end of opening 283. Exemplaryembodiment knuckle 200 and end piece 140 of steerable axle 120 arepreferably manufactured in a complementary manner to support king pin260 in a substantially vertical orientation, but can be manufacturedsuch that they have a relatively small total negative camber in a rangefrom about 0.5 degrees (0.5°) to about 5.0 degrees (5.0°) withoutaffecting the overall concept or operation of the subject disclosure.

With reference to FIGS. 2-6, exemplary embodiment knuckle 200 includes aspindle 264 that is fixed to body 266 of the knuckle by any suitablemeans, such as welding. More specifically, body 266 includes aprotrusion 268 with an outboard end portion 269 (FIG. 4) that is sizedto have inner and outer diameters substantially the same as therespective inner and outer diameters of an inboard end portion 265(FIGS. 2 and 4-6) of spindle 264. Spindle 264 preferably is frictionwelded to body 266 of knuckle 200 at an interface between inboard endportion 265 of the spindle and outboard end portion 269 of protrusion268 of the body. Protrusion 268 allows a weld site (not shown) of thefriction welding process to have good shape and relatively even weldcurls (not shown) on the protrusion and on spindle 264. The weld curlsat the weld site that are located on the outer periphery of inboard endportion 265 of spindle 264 and protrusion 268 may be machined away. Theweld curls at the weld site on the inner periphery do not interfere withthe operation or impact the strength and longevity of spindle 264, andthus knuckle 200, and may be left in place. Spindle 264 is forged of asuitable material, such as steel, and is then machine finished to haveprecise dimensions, such as for mounting components of a wheel endassembly, prior to being friction welded to protrusion 268 of body 266of knuckle 200.

Spindle 264 is oriented relative to king pin 260 such that exemplaryembodiment knuckles 200 provides the self-steering axle/suspension witha king pin leading arrangement. That is, vertical central axis C (FIG.6), through which king pin 260 extends, is located frontward of an axialcentral axis B (FIGS. 2-6) of spindle 264, which assists inself-steering and minimizes vibration or oscillation of theself-steering axle/suspension system. Vertical central axis C, throughwhich king pin 260 extends, is preferably positioned frontward of axialcentral axis B within the range of 1.5 inches to 5 inches, but could bepositioned frontward of the axial central axis at other distanceswithout affecting the overall concept or operation of the subjectdisclosure.

Spindle 264 enables mounting of a wheel end assembly (not shown) of theself-steering axle/suspension system. More specifically, the wheel endassembly includes a bearing assembly (not shown) with an inboard bearing(not shown) and an outboard bearing (not shown) that are mounted on theoutboard end of spindle 264. With reference to FIGS. 2 and 4-6, theinboard bearing abuts an outboard end 278 of a bearing shoulder 276formed on spindle 264. The outboard bearing is spaced outboardly fromthe inboard bearing on spindle 264. A spindle nut assembly (not shown)is threaded onto the outboard end of spindle 264 and secures the inboardand outboard bearings in place. A wheel hub (not shown) of the wheel endassembly is mounted on the inboard and outboard bearings for rotationrelative to spindle 264. A hub cap (not shown) is mounted on theoutboard end of the wheel hub and closes the outboard end of the wheelhub, and thus the wheel end assembly. A plurality of threaded fastenersor studs (not shown) and mating nuts (not shown) are used to mount asingle rim (not shown) or a pair of rims (not shown), depending onspecific design considerations of the wheel end assembly, to the wheelhub. A tire (not shown) is mounted on each rim. It is to be understoodthat spindle 264 could have other shapes and configurations than thatshown and described without affecting the overall concept or operationof the subject disclosure.

With reference to FIG. 6, axial central axis B (FIGS. 4-6) of spindle264 is substantially axially aligned with axial central axis A ofsteerable axle 120 when the self-steering axle/suspension system has thevehicle tires in a straight-ahead position or loaded non-turningcondition. The spindle 264 may pivot about king pin 260 in eitherdirection relative to axial central axis A of steerable axle 120 of upto about 30° from the straight-ahead position of the vehicle wheels.

With reference to FIGS. 2-6, exemplary embodiment knuckle 200 includes adiscrete tie rod arm 290 for attaching a tie rod (not shown) of theself-steering axle/suspension system, such as tie rod 66 ofself-steering axle/suspension system 10 described above. Tie rod arm 290includes a body portion 292 (FIGS. 3-6). Body portion 292 is formed withan axially extending opening (not shown) formed through the body, theimportance of which will be described below. With reference to FIGS. 3and 5-6, tie rod arm 290 further includes a mounting arm 296 that isintegrally formed with and extends frontward from body portion 292.Mounting arm 296 is formed with a vertical opening (not shown), theimportance of which will also be described below. With reference toFIGS. 2-6, tie rod arm 290 further includes a rearwardly extending tierod attachment portion 294. A vertical opening 295 is formed in tie rodattachment portion 294 adjacent the rearward end of the tie rodattachment portion.

With reference to FIGS. 3-6, tie rod arm 290 is positioned relative tobody 266 of exemplary embodiment knuckle 200 such that the outboardsurface of body portion 292 of the tie rod arm contacts and is flushwith tie rod arm attachment surface 267 (FIG. 5) of the body, and thebottom surface of mounting arm 296 (FIGS. 3 and 5-6) of the tie rod armcontacts and is flush with tie rod arm attachment surface 272 (FIG. 5)of tie rod arm mounting structure 270 (FIGS. 3-6) of the body. When tierod arm 290 is positioned relative to body 266 in this manner, theaxially extending opening formed in body portion 292 of the tie rod armis axially aligned with threaded axial opening 271 (FIGS. 4-5) formed inattachment surface 267 (FIG. 5) of the body of knuckle 200, and thevertical opening formed in mounting arm 296 (FIGS. 3 and 5-6) of the tierod arm is vertically aligned with threaded vertical opening 273 (FIG.5) formed in attachment surface 272 (FIG. 5) of mounting structure 270of the knuckle.

With reference to FIGS. 3-6, a first or axial bolt 297 is disposedthrough the axially extending opening formed in body portion 292 of tierod arm 290 (FIGS. 2-6) and threadably engages aligned axial opening 271(FIGS. 4-5) formed in tie rod arm attachment surface 267 (FIG. 5) ofbody 266 of knuckle 200. With reference to FIGS. 3 and 5-6, a second orradial bolt 299 is disposed through the vertical opening formed inmounting arm 296 of tie rod arm 290 and threadably engages alignedvertical opening 273 formed in tie rod arm attachment surface 272 (FIG.5) of mounting structure 270 (FIGS. 3-6) of knuckle 200. In this manner,tie rod arm 290 is removably secured to body 266 of exemplary embodimentknuckle 200. Tie rod arm 290 supports pivotal attachment of the tie rod(not shown), such that an axial central axis (not shown) of the tie rodis positioned parallel to axial central axis A of steerable axle 120(FIG. 6) when the vehicle wheels are in the straight-ahead position.

Exemplary embodiment knuckle 200 also includes structure to accommodatecomponents of a tire inflation system, as well as vent an interior ofthe wheel end assembly mounted on spindle 264, for example, during apressure build-up within the wheel end assembly from a leak of a tireinflation system component. More specifically, and with reference toFIGS. 3 and 5-6, body 266 of knuckle 200 is formed with a first axialopening 230 extending through the body at a location positioned radiallyinwardly of protrusion 268 (FIG. 4), such that when spindle 264 isattached to the protrusion, the first axial opening is in fluidcommunication with an interior 274 (FIGS. 2 and 4) of the spindle. Firstaxial opening 230 is sized such that it enables a pneumatic line of atire inflation system (not shown) of a type known in the art to bedisposed through the opening and extend from the exterior of knuckle 200into interior 274 (FIGS. 2 and 4) of spindle 264, and ultimately toother components (not shown) of the tire inflation system incorporatedinto the wheel end assembly, such as a wheel valve and rotary union, tosupport inflation of the tire(s) of the wheel(s) rotatably mounted onthe spindle via the wheel hub.

With reference to FIG. 3, exemplary embodiment knuckle 200 includes avent system 240 incorporated into the knuckle. With reference to FIGS.4-6, vent system 240 includes an axial opening 244 that extends throughbody 266 of knuckle 200 at a location positioned radially inwardly ofprotrusion 268 (FIG. 4), such that when spindle 264 is attached to theprotrusion, the axial opening is in fluid communication with interior274 (FIGS. 2 and 4) of the spindle. With reference to FIG. 3, apneumatic check valve 246 of vent system 240 is attached to axialopening 244 on the inboard surface of body 266 of knuckle 200. A venttube 248 in turn is connected to check valve 246 via a hose clamp 249.

Upon a pressure build-up within the wheel end assembly mounted onspindle 264 of exemplary embodiment knuckle 200, such as from a leak ofa tire inflation system component, vent system 240 of the knuckleenables pressurized air to be vented from the interior of the wheel endassembly to atmosphere. More specifically, pressurized air from withinthe wheel end assembly is able to flow from the interior of the wheelend assembly, through interior 274 (FIGS. 2 and 4) of spindle 264, axialopening 244, check valve 246, vent tube 248, and to atmosphere. It iscontemplated that exemplary embodiment knuckle 200 could employ ventsystem 240 in self-steering axle/suspension system configurations thatdo not utilize tire inflation systems. In such configurations, as apneumatic line does not pass through first axial opening 230 formed inbody 266 of knuckle 200, the first axial opening may be plugged viasuitable means. In this manner, vent system 240 of knuckle 200 preventspressure build-ups within components of the wheel end assembly mountedon spindle 264 and reduces the potential for damage to the components,such as associated seals (not shown) and bearings (not shown), from suchpressure build-ups.

In accordance with an important aspect of the subject disclosure,exemplary embodiment knuckle 200 includes structure integrated into theknuckle for mounting components of a drum brake assembly 302 of a drumbrake system 300. More specifically, and with reference to FIGS. 2-6,body or brake spider portion 266 of knuckle 200 is formed with a pair ofbrake shoe mounting openings 277 adjacent a top end of the body. Brakeshoe openings 277 enable pivotal mounting of an upper brake shoe 304Aand a lower brake shoe 304B (FIGS. 2-3). More specifically, and withreference to FIGS. 2-3, an anchor pin 308 is disposed within and extendsthrough each one of openings 277. Each anchor pin 308 may be slip fitwithin a respective bushing (not shown) disposed within a respectivebrake shoe opening 277. Brake shoes 304A and 304B each include arespective pair of side walls 305A and 305B that are rotatably connectedto respective ones of anchor pins 308 in a manner known in the art. Eachbrake shoe 304A and 304B includes a brake shoe table 306A and 306B,respectively, that is rigidly attached to respective side walls 305A and305B by suitable means, such as welds. Each brake shoe 304A and 304Balso includes a respective pair of brake pads 307A and 307B that areattached to a respective one of brake shoe table 306A and 306B via arespective plurality of fasteners 309A and 309B, such as rivets. It isto be understood that body or brake spider portion 266 of knuckle 200could be formed with only a single brake shoe mounting opening 277adjacent the top end of the body with an anchor pin 308 disposed thereinto support a single anchor pin drum brake system configuration withoutaffecting the overall concept or operation of the subject disclosure. Insuch a configuration, anchor pin 308 may be interference fit within thesingle brake shoe mounting opening 277 or slip fit within a bushing (notshown) disposed within the single brake shoe mounting opening.

With reference to FIG. 2, first resilient retaining members (not shown),preferably coiled tension springs, referred to in the art as retainingsprings, are connected to and extend between respective first openings310A (only one shown) formed in side walls 305A and first openings 310B(only one shown) formed in side walls 305B of brake shoes 304A and 304B,respectively, near the pivotal connection of the side walls to anchorpins 308. Second resilient retaining members (not shown), preferablyalso coiled tension springs, referred to in the art as return springs,are connected to and extend between respective second openings 311Aformed in side walls 305A and second openings (not shown) formed in sidewalls 305B of brake shoes 304A and 304B, respectively. The secondresilient retaining members retain the ends of side walls 305A and 305Bof brake shoes 304A and 304B, respectively, opposite their pivotalconnections to anchor pins 308 to a respective roller 312A and 312B.

Exemplary embodiment knuckle 200 also includes structure that enablesmounting of a cam bracket assembly 320 of drum brake assembly 302. Morespecifically, and with reference to FIGS. 2, and 4-6, body 266 ofknuckle 200 is formed with a cam tube opening 279 adjacent a bottom endof the body. Cam tube opening 279 extends axially through body 266,including through tie rod arm mounting structure 270 of the body. Camtube opening 279 is sized to accommodate a cam tube 322 of cam bracketassembly 320 (FIGS. 2-3), which is disposed within the opening. Cam tube322 is rigidly attached to body 266 within cam tube opening 279 by anysuitable means, such as welds. Cam bracket assembly 320 includes a camshaft (not shown), which is disposed through and rotatably mountedwithin cam tube 322. More specifically, the cam shaft passes throughoutboard and inboard bushings (not shown) that are friction fit withinthe outboard and inboard ends of cam tube 322, respectively, and extendsoutboardly and inboardly of the outboard and inboard ends of the camtube, respectively. The outboard and inboard bushings within cam tube322 enable rotation of the cam shaft within the cam tube. The cam shaftincludes a splined inboard end (not shown) that extends inboardly fromthe inboard end of cam tube 322. The splined inboard end of the camshaft meshingly engages a corresponding splined interior surface (notshown) of a slack adjuster (not shown) of drum brake assembly 302. Cambracket assembly 320 further includes an S-cam (not shown) that isattached to the outboard end of the cam shaft, such that the S-cam isexposed and is located outboard of and adjacent to the outboard end ofcam tube 322 and operatively engages rollers 312A and 312B (FIG. 2) in amanner known in the art.

With reference to FIGS. 2-3, a brake air chamber mounting bracket 326 isrigidly attached to the inboard end of cam tube 322 by any suitablemeans, such as welds. Brake air chamber mounting bracket 326 is formedwith a pair of openings 327 (FIG. 3) that enable mounting of a brake airchamber (not shown) of a type known in the art that is operativelyconnected to an air source located on the heavy-duty vehicle via apneumatic line. A push rod (not shown) slidably and operativelyconnected to the brake air chamber extends rearward from the brake airchamber and through a notch 328 formed in the bracket. The rearward endof the push rod is pivotally attached to the slack adjuster in a knownmanner.

During braking of the heavy-duty vehicle, in response to a brakecommand, the pressurization of the brake air chamber forces the push rodrearward and causes rotation of the slack adjuster at the splinedconnection of the slack adjuster to the cam shaft, which in turn causesthe cam shaft to rotate within cam tube 322 of cam bracket assembly 320.This in turn causes the S-cam to engage rollers 312A and 312B. Rollers312A and 312B in turn contact respective side walls 305A and 305B ofbrake shoes 304A and 304B. The S-cam causes each roller 312A and 312B tomove in a generally radially outward direction, reacting against eachrespective anchor pin 308 and overcoming the force of the firstresilient retaining members and second resilient retaining membersconnected to respective side walls 305A and 305B of brake shoes 304A and304B. When the force of the first resilient retaining members and secondresilient retaining members are overcome, brake shoes 304A and 304Bpivot about anchor pins 308, such that the brake shoes move radiallyoutwardly. As brake shoes 304A and 304B move radially outwardly, theirrespective brake pads 307A and 307B contact an inner surface of a brakedrum attached to the wheel hub of the wheel end assembly rotatablymounted on spindle 264 of exemplary embodiment knuckle 200 to slow orstop the heavy-duty vehicle. When the braking operation is complete, thefirst resilient retaining members and second resilient retaining membersmove each brake shoe 304A and 304B generally radially inward to anon-applied position, as known in the art.

Because body 266 of exemplary embodiment knuckle 200 enables componentsof drum brake assembly 302 of drum brake system 300 to be directlymounted on the knuckle, including brake shoes 304A and 304B and cam tube322, the knuckle eliminates the need for a discrete brake spider to berigidly attached to a spindle end, such as brake spider 80 attached tospindle end 68 of prior art knuckle 58, to support mounting of such drumbrake assembly components. This in turn eliminates the relativelycomplex manufacturing process and additional components required forpreparing a spindle end for mounting and attaching a discrete brakespider, such as that required to mount and attach discrete brake spider80 to spindle end 68 of prior art knuckle 58, thereby reducing theoverall manufacturing complexity and cost of exemplary embodimentknuckle 200 as compared to prior art knuckles.

In addition, because structure for mounting components of drum brakeassembly 302 of drum brake system 300, including brake shoe mountingopenings 277 and cam tube opening 279, is integrated into body 266 ofknuckle 200, and the need to mount a discrete brake spider on a spindleof the knuckle to mount components of the drum brake assembly iseliminated, the overall length of spindle 264 can be reduced compared tospindle ends of prior art knuckles that require mounting of a discretebrake spider, such as spindle end 68 of prior art knuckle 58 to whichbrake spider 80 is mounted and attached. Consequently, exemplaryembodiment knuckle 200 enables a distance D (FIG. 6) between outboardend 278 of bearing shoulder 276 and vertical central axis C, along whichking pin 260 extends, to be reduced compared to the prior art. DistanceD is preferably within the range of about 7.5 inches to about 10.5inches, and more preferably within the range of about 8.5 inches toabout 9.5 inches. This in turn enables the wheel hub rotatably mountedon the inboard and outboard bearings mounted on spindle 264 to be incloser inboard proximity to the pivotal connection of knuckle 200 to endpiece 140 of steerable axle 120 via king pin 260, which shortens thedistance between a vertical centerline (not shown) of the wheelconnected to the wheel hub and vertical central axis C (FIG. 6), alongwhich king pin 260 extends, compared to the prior art. Moreover,exemplary embodiment knuckle 200 enables a distance E (FIG. 6) between avertical centerline of brake shoe mounting openings 277, and thus avertical centerline of brake shoes 304A and 304B, and vertical centralaxis C, along which king pin 260 extends, to be reduced compared toprior art knuckles, such as prior art knuckle 58. Distance E ispreferably within the range of about 4.0 inches to about 7.0 inches, andmore preferably within the range of about 4.5 inches to about 6.0inches. This overall less cantilevered design reduces stress and fatigueof knuckle 200 and the pivotal connection of the knuckle to end piece140 of steerable axle 120, and thus reduces the potential for prematurefailure of the knuckle and/or knuckle to end piece connection.

In accordance with another important aspect of the subject disclosure,because tie rod arm 290 is connected to body 266 of exemplary embodimentknuckle 200 via first bolt 297 and second bolt 299, the tie rod arm isremovable from the knuckle, and thus the self-steering axle/suspensionsystem. This enables exemplary embodiment knuckle 200 to providesufficient flexibility and robustness during assembly of a self-steeringaxle/suspension employing the exemplary embodiment knuckle(s) so thatthe knuckle(s) can be incorporated into and utilized with self-steeringaxle/suspension systems with varying components and configurationsdifferent than those shown and described, such as fabricated top mountself-steering axle/suspension systems.

Moreover, the configuration and manner in which tie rod arm 290 isconnected to body 266 of exemplary embodiment knuckle 200 minimizes theoverall required size of the knuckle, while providing a sturdy structurethat resists overload conditions, which reduces the overall weight ofthe heavy-duty vehicle, provides desired turn angle of the knuckle andmounted wheel, and provides desired strength to the knuckle. Morespecifically, and with particular reference to FIGS. 5-6, second bolt299 is disposed through the vertical opening formed in mounting arm 296of tie rod arm 290 and threadably engages threaded vertical opening 273formed in tie rod arm attachment surface 272 of mounting structure 270,and first bolt 297 is disposed through the axially extending openingformed in body portion 292 of tie rod arm 290 and threadedly engagesaxial opening 271 formed in tie rod arm attachment surface 267 of body266, such that the first and second bolts are positioned about ninetydegrees (90°) from one another in offset axial and vertical planes,respectively. In addition, first bolt 297, which is the attachment pointof tie rod arm 290 to body 266 closest in proximity to the connection ofthe tie rod to tie rod attachment portion 294 of the tie rod arm,provides an axial connection of the tie rod arm to the body of theknuckle. This attachment configuration of tie rod arm 290 to body 266provides a generally sturdy and robust connection with sufficientclamping force capable of resisting overload conditions, without failureof the tie rod arm or loosening of the connection of the tie rod to thetie rod arm and/or the connection of the tie rod arm to the body ofknuckle 200.

Moreover, because second bolt 299 is disposed through the verticalopening formed in mounting arm 296 of tie rod arm 290 and threadablyengages threaded vertical opening 273 formed in tie rod arm attachmentsurface 272 of mounting structure 270, sufficient clearance exists toenable exemplary embodiment knuckle 200 to provide up to a thirty-degree(30°) wheel cut for the wheel associated with the knuckle, as well asaccommodate mounting and provide clearance for cam tube 322 of cambracket assembly 320 disposed within cam tube opening 279 formed in body266 of knuckle 200.

Thus, exemplary embodiment knuckle for a self-steering axle/suspensionsystem 200 of the subject disclosure includes an integrally formedstructure for mounting components of a drum brake system, whicheliminates complex manufacturing processes for preparing a spindle endof the knuckle capable of mounting a discrete brake spider and machiningof multiple interfaces on the spindle end to position and attach thediscrete brake spider, thereby reducing manufacturing complexity andcost. Exemplary embodiment knuckle 200 includes a spindle that isforged, machine finished, and then friction welded directly to theknuckle with only a single friction weld, which eliminates the need toutilize multiple welds to attach the spindle to the knuckle and thebrake spider to the spindle, thereby reducing manufacturing costs andincreasing the overall strength of the spindle. Also, by integratingstructure for mounting drum brake system components into exemplaryembodiment knuckle 200, the distance from the brake spider to the kingpin, and consequently the bearing shoulder of the spindle to the kingpin, and thus the distance from the king pin to a vertical centerline ofa wheel mounted on the spindle, is minimized, which reduces stress onthe knuckle and the pivotal connection of the knuckle to an end piece ofa steerable axle, thereby increasing the overall strength and reducingfatigue of the knuckle and pivotal connection of the knuckle to thesteerable axle, and reducing the risk for potential premature failure ofthe knuckle and/or pivotal connection of the knuckle to the steerableaxle. In addition, exemplary embodiment knuckle 200 includes a discretetie rod arm bolted to the knuckle via axial and radial bolting in amanner that minimizes the overall size and weight of the knuckle, whileproviding a sturdy structure that resists overload conditions, whichreduces the overall weight of the heavy-duty vehicle, provides desiredturn angle of the knuckle and mounted wheel, and provides the knucklewith a robust structure capable of being utilized on self-steeringaxle/suspension systems with varying components and configurations.

It is to be understood that the knuckle for a heavy-duty vehicleself-steering axle/suspension system of the subject disclosure findsapplication in all types of self-steering axle/suspension systems knownto those skilled in the art, including those with other components andconfigurations than those shown and described herein, without affectingthe concept or operation of the subject disclosure. It is also to beunderstood that the knuckle for a heavy-duty vehicle self-steeringaxle/suspension system of the subject disclosure can include othershapes and configurations than that shown and described withoutaffecting the overall concept or operation of the subject disclosure. Itis to be further understood that the knuckle for a heavy-duty vehicleself-steering axle/suspension system of the subject disclosure can beutilized in conjunction with drum brake systems with components andconfigurations different than those shown and described withoutaffecting the overall concept or operation of the subject disclosure,such as those including single anchor pin configurations.

Accordingly, the knuckle for a heavy-duty vehicle self-steeringaxle/suspension system of the subject disclosure is simplified, providesan effective, safe, inexpensive, and efficient structure which achievesall the enumerated objectives, provides for eliminating difficultiesencountered with prior art knuckles for heavy-duty vehicle self-steeringaxle/suspension systems, and solves problems and obtains new results inthe art.

In the foregoing description, certain terms have been used for brevity,clarity and understanding; but no unnecessary limitations are to beimplied therefrom beyond the requirements of the prior art, because suchterms are used for descriptive purposes and are intended to be broadlyconstrued. Moreover, the subject disclosure has been described withreference to a specific embodiment. It shall be understood that thisillustration is by way of example and not by way of limitation, as thescope of the invention is not limited to the exact details shown ordescribed. Potential modifications and alterations will occur to othersupon a reading and understanding of the subject disclosure, and it isunderstood that the subject disclosure includes all such modificationsand alterations and equivalents thereof.

Having now described the features, discoveries and principles of thesubject disclosure, the manner in which the knuckle for a heavy-dutyvehicle self-steering axle/suspension system is constructed, arrangedand used, the characteristics of the construction and arrangement, andthe advantageous, new and useful results obtained; the new and usefulstructures, devices, elements, arrangements, parts and combinations areset forth in the appended claims.

What is claimed is:
 1. A knuckle for a self-steering axle/suspensionsystem for a heavy-duty vehicle having a drum brake system, said knucklecomprising: a body, said body receiving a king pin of said self-steeringaxle/suspension system for pivotal connection of said knuckle to an axleof the self-steering axle/suspension system; a spindle extending from anoutboard surface of the body; and drum brake system component mountingstructure, said drum brake system component mounting structure beingintegrally formed with the body and mounting one or more components ofsaid drum brake system.
 2. The knuckle for a self-steeringaxle/suspensions system for a heavy-duty vehicle of claim 1, whereinsaid spindle is fixed to said body via a single weld.
 3. The knuckle fora self-steering axle/suspensions system for a heavy-duty vehicle ofclaim 2, wherein said single weld is a friction weld.
 4. The knuckle fora self-steering axle/suspension system for a heavy-duty vehicle of claim1, wherein a distance between an outboard end of a bearing shoulder ofsaid spindle and a vertical axis extending through said king pin iswithin about 7.5 inches to about 10.5 inches.
 5. The knuckle for aself-steering axle/suspension system for a heavy-duty vehicle of claim1, wherein a distance between an outboard end of a bearing shoulder ofsaid spindle and a vertical axis extending through said king pin iswithin about 8.5 inches to about 9.5 inches.
 6. The knuckle for aself-steering axle/suspension system for a heavy-duty vehicle of claim1, wherein said body includes a first arm and a second arm extendingfrom an inboard surface of the body, said first arm having an openingfor receiving a first end portion of said king pin of said self-steeringaxle/suspension system, said second arm having an opening coaxiallyaligned with said opening in the first arm for receiving an oppositesecond end portion the king pin.
 7. The knuckle for a self-steeringaxle/suspension system for a heavy-duty vehicle of claim 1 furthercomprising a discrete tie rod arm, said tie rod arm being removablyconnected to said body of said knuckle without welds.
 8. The knuckle fora self-steering axle/suspension system for a heavy-duty vehicle of claim7, said tie rod arm being connected to said body via a first fastenerand a second fastener, said first fastener being positioned offsetaxially and vertically from said second fastener.
 9. The knuckle for aself-steering axle/suspension system for a heavy-duty vehicle of claim8, wherein said first fastener is positioned about 90 degrees offsetaxially and vertically from said second fastener.
 10. The knuckle for aself-steering axle/suspension system for a heavy-duty vehicle of claim9, wherein said first fastener and said second fastener are bolts. 11.The knuckle for a self-steering axle/suspension system for a heavy-dutyvehicle of claim 1, wherein said drum brake component mounting structureincludes at least one brake shoe opening to which a brake shoe ispivotally connected.
 12. The knuckle for a self-steering axle/suspensionsystem for a heavy-duty vehicle of claim 1, wherein said drum brakecomponent mounting structure includes a pair of brake shoe openings, abrake shoe being pivotally connected to each one of said pair of brakeshoe openings.
 13. The knuckle for a self-steering axle/suspensionsystem for a heavy-duty vehicle of claim 1, wherein said drum brakecomponent mounting structure includes a cam tube opening through which acam tube of a cam bracket assembly is disposed.
 14. The knuckle for aself-steering axle/suspension system for a heavy-duty vehicle of claim1, said body further including a protrusion extending outboardly fromthe body, said spindle being fixed to an outboard end of said protrusionvia friction welding.
 15. The knuckle for a self-steeringaxle/suspension system for a heavy-duty vehicle of claim 1, said knucklefurther comprising structure for accommodating one or more components ofa tire inflation system, said structure including a first axial opening,said first axial opening extending through said body at a locationpositioned radially inward of said spindle, the first axial openingbeing sized to enable passage of a pneumatic line of a tire inflationsystem through said first axial opening and into an interior of thespindle.
 16. The knuckle for a self-steering axle/suspension system fora heavy-duty vehicle of claim 15, further comprising a vent systemincorporated into said knuckle, said vent system including: a secondaxial opening extending through said body at a location positionedradially inward of said spindle; and a pneumatic check valve, saidpneumatic check valve being attached to said second axial openingadjacent an inboard surface of the body, said pneumatic check valveenabling pressurized air to be vented from said interior of the spindleto atmosphere.
 17. The knuckle for a self-steering axle/suspensionsystem for a heavy-duty vehicle of claim 1, further comprising a ventsystem incorporated into said knuckle, said vent system including: anaxial opening extending through said body at a location positionedradially inward of said spindle; and a pneumatic check valve, saidpneumatic check valve being attached to said axial opening adjacent aninboard surface of the body, said pneumatic check valve enablingpressurized air to be vented from an interior of the spindle toatmosphere.
 18. The knuckle for a self-steering axle/suspension systemfor a heavy-duty vehicle of claim 6, wherein said drum brake systemcomponent mounting structure, said body, said first arm, and said secondarm are integrally formed.
 19. The knuckle for a self-steeringaxle/suspension system for a heavy-duty vehicle of claim 18, whereinsaid brake component mounting structure, said body, said first arm, andsaid second arm are integrally formed via forging.
 20. The knuckle for aself-steering axle/suspension system for a heavy-duty vehicle of claim1, wherein said knuckle provides up to a thirty-degree wheel cut for awheel mounted on said spindle.
 21. The knuckle for a self-steeringaxle/suspension system for a heavy-duty vehicle of claim 1, wherein saidself-steering axle suspension/system is a trailing arm self-steeringaxle/suspension system and a vertical central axis of said king pin islocated frontward of an axial central axis of said spindle.